360....for no other reason than they are a cinch to mod. Takes me under 20 mins. Hardware is easy to work on, its like the VW Bug of the gaming world.. Microsoft will never learn, original xbox was even worse
PS3 no doubt - my 360 had to be serviced 5 times, first time straight out the box when the supply went up in flames ... so the MS quality isnt what I expect from a vendor ...
I would say PS3. 360 games are almost always available on the PC as well, plus the online for the PS3 is free. The only downside is that you cannot play downloaded PS3 games (as far as I know). Furthermore, the PS3 is a blu-ray player.